Since we know Mary's speed AND direction, we have
all the information we need to state her velocity.
The difference is that physical weathering is a process that weathers rock without a chemical reaction or change. Chemical weathering changes the identity of rocks and it involves a chemical reaction or change.
I believe that we dream because we have memories of what have happened or what we have seen in the day
Exercising
Meditating
Writing journals
Spending time with positive thinking people